The TFTP server sends a request for all configuration files, phone
loads, audio files, and so forth. Even when the phone boots up for the first
time with the new TFTP server, it sends a TFTPRequestNotFound
error message because it is in the process of creating the file for the first
time.

The TFTPRequestNotFound error message always shows
some failed requests for the IP phone that have registered for the first time,
or for IP phones that are deleted, but have their CNF files in the TFTP server.
You can solve this when you disable the caching of the startup and
configuration files and then recreate them.

From the CallManager Administration page, choose
Service > Service Parameters.

Select your TFTP server from the drop-down list, select
Cisco TFTP service, click the Advanced tab
and then set these parameters:

Set Build CNF Files to Build
All.

Set Enable Caching of Constant and Bin Files at Startup to
False.

Set Enable Caching of Configuration Files to
False.

Click on Update and restart the TFTP
service.

Note: This recreates the configuration files and might take a long time
if a large number of devices exist on the network.